I doubt Verizon would be able to keep up with iPhone users either. 3.2 mil per quarter is HUGE. Heck, Verizon around here started to choke at 1mil per quarter back in '04.
No issues here with AT&T. Although I've noticed dropped calls seem to be up, but I hope they are just tweaking their network.
And T-Mo has even LESS coverage than AT&T. Been there, done that, never again.